2.5.2 docs (#247)

* docs: Changes for v2.5.2 release

* docs: Remove -X POST

Curl automatically uses POST for -d and --data-binary.

I intentionally left it in to be explicit to learners, but
maybe best practices are better.

* api: /adapt endpoint and Etag usage

* api: Minor tweaks

* Alright fine

* Clarify Etag usage

* CEL embedded matchers

* Oops

* Lots more adjustments

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

src/docs/markdown/quick-starts/api.md

@@ -17,7 +17,6 @@ First start Caddy:
 Caddy is currently running idle (with a blank configuration). Give it a simple config with `curl`:
 
 <pre><code class="cmd bash">curl localhost:2019/load \
-    -X POST \
     -H "Content-Type: application/json" \
     -d @- << EOF
     {
@@ -44,7 +43,6 @@ EOF</code></pre>
 Giving a POST body with [Heredoc](https://en.wikipedia.org/wiki/Here_document#Unix_shells) can be tedious, so if you prefer to use files, save the JSON to a file called `caddy.json` and then use this command instead:
 
 <pre><code class="cmd bash">curl localhost:2019/load \
-  -X POST \
   -H "Content-Type: application/json" \
   -d @caddy.json
 </code></pre>